Dye Wastewater Research Articles

Comparison study of aluminum (Al)-doped strontium titanate (SrAlxTi1-xO3; x = 3 % and 5 %) photocatalyst for Methylene blue degradation

One famous photocatalyst to degrade methylene blue (MB) dye wastewater is SrTiO3 (strontium titanate or STO), whose performance can be enhanced by doping Aluminum (Al). This study aimed to fabricate Al-doped STO (SrTi1-xAlxO3; x = 3 % and 5 %) photocatalysts and compare the effects of low Al concentrations on photocatalytic performance. The photocatalysts were fabricated using a coprecipitation route and confirmed by XRD and FTIR instruments. The photocatalytic performance of Al-doped STO against MB was tested under varied UV light exposure hours and examined using a UV–Vis Spectrophotometer. In conclusion, Al-doped STO 3 % demonstrated better photocatalytic performance with a higher %degradation and faster degradation rate.

The Optimization of Hydrodynamic Cavitation as an Advanced Oxidation Option for the Removal of Persistent Contaminants in Wastewater

Wastewater is increasingly becoming the primary source of potable water in many cities, thanks to the development of recycling facilities. Persistent contaminants such as dyes and perfluorinated compounds from textile industries as well as other contaminants necessitate the design of removal technologies to treat wastewater to reduce these chemicals before discharge or being used as feed to a potable water plant. Several chemical treatment techniques have been reported but the most utilized advanced chemical treatments lead to high costs and further environmental concerns. This study investigated an alternative approach to wastewater treatment using a hydrodynamic cavitation pilot plant combined with a venturi as a way to remove recalcitrant compounds. The optimization of the removal process was explored by testing the effect of orifices with size 2, 3, 4, 5, or 6 mm on the decoloration of orange II dye. The impact of the catalyst: iron(II); oxidizing agent: hydrogen peroxide; and contact time was evaluated to find the ideal conditions under which the removal of perfluorooctanoic acid (PFOA) could be achieved. The decoloration of 20 ppm of orange II dye in simulated industrial textile wastewater was achieved at 90% efficiency when the pressure at the inlet was maintained at 300 kPa, the temperature at 34 °C, the pH at 2, and the orifice size at 2 mm of diameter. The kinetic study proved the decoloration reaction was pseudo first order and the rate of decolourisation of orange II was 0.23/min.Ten parts per million of PFOA could not be degraded by free radical attack using advanced oxidation processes when the inlet pressure was maintained at 300 kPa, the temperature at 34 °C, the pH of 2, and the orifice diameter of 2 mm. This resistance to removal is due to the structure of PFOA which is made up of a fluorine ion which stabilizes the compounds by inductive effects while dye is made up of nitrogen ion and is compatible with the above removal methods. The study demonstrated that the combination of venturi and orifice requires the throat size of the venturi to be similar or equal to that of the orifice for better efficiency.

Comparative study between bulk and surface modification on hy-drophobic membrane for dyeing and oily wastewater treatment

Surface modification could remarkably improve the oil–water separation ability of membrane, but suffers from limited survival positive effect layer after long-term operation. Herein, we report a systematic comparative study between bulk and surface modification (i.e., synchronous or sequential electrospun/elecrospraying) on hydrophobic polyvinylidene difluoride (PVDF) membrane. A hydrophilic UiO-66-NH2@polyacrylic acid micro/nanospheres (UiO@PAA) was selected as functional layer to improve the separation and adsorption capability of PVDF. The surface modification (SMM) and bulk modification membranes (BMM) exhibited the similar water wetting behavior in air as the same surface layer. The spider filament-like nanofibers of BMM could enhance the mechanical stability and dispersion uniformity of active sites among the PVDF fibers. In terms of oil-in-water emulsions separation ability, the BMM was superior to the SMM with the maximumly increase of separation efficiency and filtration flux to 1.3 % and 192.6 L m-2h−1, respectively. As for dye absorption, the BMM showed better adsorption capacity with a removal efficiency over 96 %. For the low concentration of methylene blue, the removal efficiency of SMM was only 94 %, while the removal efficiency of the BMM reached 98 % at room temperature. In addition, the BMM exhibited higher removal efficiency over 94 % compared with that less than 84 % of SMM after eight cycling tests, confirming its advantages in repeatability. This study demonstrates that the bulk modification can endow the initial membrane with better performance and durability, showing more promising prospects in actual wastewater treatment.

Continuous flow combined with in situ self-assembly fabrication of high permselective ZIF-8@GO composite membrane in ceramic tube for organic dye nanofiltration

Nanofiltration holds promise for treating dyeing and printing wastewater on account of its key merits: low consumption, easy manipulation, and absence of secondary contamination. In this study, the fabrication of a uniform permselective ZIF-8@GO composite membrane in the alumina ceramic tube by the continuous flow combined with in situ self-assembly way was investigated. Subsequently, the properties of ZIF-8@GO membrane were examined in relation to reaction time, reaction temperature, flow rate, and GO concentration. Furthermore, the durability of the membrane was tested. It was observed that under optimal conditions, the rejection rate and permeation flux of methyl blue solutions remained essentially constant during 24 hours of continuous operation, with values of 98.39% and 38.27 L/(m2·h·bar), respectively. This work aims to simplify and smoothly implement the industrialized production of MOF-based composite membranes and offers a potential solution for the low-cost and efficient treatment of organic dye wastewater in the printing and dyeing industry.

Multivariate Statistical Analysis of Dyeing Wastewater Organic Matter Indicators

Objectives:Since 2016, TOC (Total Organic Carbon) has replaced COD (Chemical Oxygen Demand) as an organic indicator for effluent wastewater quality standards. However, the distribution of organic substances by process in wastewater treatment facilities is not properly identified, making it difficult to secure stable treated wastewater quality. Therefore, in this study, we identified the correlation between TOC and existing organic matter indicators in raw wastewater, primary treated, secondary treated, and effluent wastewater for dyeing wastewater.Methods:Samples for each process were collected twice a week, a total of 24 times, from a dyeing wastewater treatment plant located in Y-city, Gyeonggi-do, and organic pollutant indicators (TOC, COD<sub>Cr</sub>, COD<sub>Mn</sub>, BOD<sub>5</sub>) were analyzed. TOC was analyzed by the NPOC (non-purgeable organic carbon) method using TOC-VCHP (Shimadzu, Japan). Using the analysis results, the characteristics of organic pollutants in dyeing wastewater were analyzed. In addition, multivariate statistical analysis was performed using SPSS to analyze correlations between organic pollutant indicators and principal component analysis.Results and Discussion:As a result of multivariate statistical analysis, TOC was inflowed at an average of 574.9 mg/L and treated at 58.2mg/L. In the case of COD<sub>Cr</sub>, COD<sub>Mn</sub>, and BOD<sub>5</sub>, the inflow was 1,644, 448.9, and 440.7 mg/L and was treated at 98.2, 39.7, and 10.8mg/L. When evaluated based on effluent water quality standards, all of them satisfied the Region III standards, but were discharged at a relatively high level compared to the TOC concentration of sewage treatment plants effluent. As a result of comparing correlations between organic matter indicators through Pearson correlation analysis, the inflow raw water shows a high positive correlation with TOC:TCOD<sub>Cr</sub> (r=0.720), TOC:TCOD<sub>Mn</sub> (r=0.636), and TOC:TBOD<sub>5</sub> (r=0.302) showed low correlation. This is reason to be due to the fact that most organic substances in dyeing wastewater are non-degradable substances and have low biodegradability. As a result of principal component analysis of influent, primary treated, and final treated, three main components each (two for final treated) were extracted, with cumulative contribution rates of 80.1%, 83.2%, and 95.6%.Conclusion:Because the properties of wastewater differ greatly depending on the type of leather and chemicals handled at the dyeing factory, the correlation between influent water was low, but the correlation between treated water and treated water was relatively high. The correlation between processes in wastewater treatment facilities also tended to increase toward later processes. It is believed that the above statistical analysis can be used as basic data for effective organic matter management.

Bio-composite of chitosan and polyethylene for the biosorption of dye in wastewater

This study investigated the potential of a biocomposite adsorbent made of low-density polyethylene-chitosan nanoparticles (LDPE/CHNP) for removing Congo red and Crystal violet dyes from wastewater. Batch experiments were conducted at room temperature to study the effects of pH, contact time, initial concentration, adsorbent dosage, and temperature on the adsorption process. The results showed that the maximum sorption of Congo red and Crystal violet occurred at pH 8. The adsorption process was rapid in the first 30 minutes of contact, with more than 90% uptake, and equilibrium was achieved with 150 rpm agitation. The biosorption of Congo red and Crystal violet dyes was described using Langmuir, Freundlich, and isotherm models. The Langmuir model was found to fit the equilibrium data better, with a correlation coefficient of 0.99 and a maximal adsorption capacity of 27.1 mg/g. Based on these results, it can be concluded that the biocomposite adsorbent made of low density polyethylene-chitosan nanoparticles (LDPE/CHNP) has the potential to be an effective and abundant alternative biomass for removing these dyes from wastewater. The LDPE/CHNP biocomposite adsorbent could be applied as a remediation method for color contamination in wastewater.

Flocculation of kaolin and anion dye by cationic cellulose-based flocculant: RSM-optimized synthesis and experimental study

An efficient cellulose-based flocculant, CMA, was synthesized using a free radical initiation method in a NaOH/Urea aqueous solution. The optimal synthesis conditions were determined through single-factor and RSM experiments: a molar ratio of MCC to AA of 1:3.6, MCC to CTA of 1:8.2, and a reaction temperature of 45.8 °C. CMA was characterized using FTIR, SEM, XRD, DLS, XPS, and TG and applied successfully to the flocculation treatments of kaolin, simulated dyes, and actual dye wastewater. It exhibited low pH sensitivity, achieving over 90% removal efficiency at pH 3–12, with a maximum of 98.3%. In simulated dye wastewater, the removal efficiency of various dyes was greater than 95%, with a maximum of 97%. After CMA flocculation and ozone aeration, 86.5% of COD and 93.6% of turbidity were removed from the actual dye wastewater. CMA carried out the flocculated dye removal process via charge neutralization, double layer compression, and bridging adsorption, as revealed by various instrument characterization and analysis. A polysaccharide-based flocculant, CMA exhibits environmentally friendly properties, low pH sensitivity, and high efficiency in removing wastewater pollutants, making it a promising flocculant for highly turbid wastewater and anionic dye wastewater.

Nanocomposite ceramic membranes as novel tools for remediation of textile dye waste water – A review of current applications, machine learning based modeling and future perspectives

Textile effluent treatment has gained significant attention due to the carcinogenic effects of the dye pollutants present and their enhanced resistance to degradation. Porous ceramic membranes have gained growing interest for dye remediation due to various unique characteristics, including resistance to fungal invasion, adverse chemical conditions, and high temperature. The current study explores applications of ceramic membrane technology, including membranes like MF, UF, and NF, for dye remediation from textile effluent. The best-performing nanocomposite membranes for eliminating azo dyes from textile effluent and efficiencies achieved are reported as Clay-alumina (99%), yttria-stabilized-zirconia (99%), nano TiO2-bentonite UF (95%), and tight TiO2 UF (100%). Ceramic nanocomposites with TiO2 and Al2O3 active layer NF (99%), Ceramic Hybrid hollow fiber LNF (99.3%). Loose nanofiltration (LNF) ceramic membranes have demonstrated outstanding targeted separation performance for the separation of dyes, making them affirm the effective recoveries and recurrent use of high-value-added constituents amongst all the membrane approaches examined. The potential of ceramic membranes for future research and development, including membrane production and mechanism, are discussed. In addition, the implementation of AI-based methods and Machine learning (ML) algorithms are discussed in relation to predicting membrane filtration performance and fouling tendencies and dye removal processes, maximizing opportunities in this field.

Multitasking needle-shaped copper oxide nanorods decorated cystine modified polymer/graphene oxide nanocomposite for 4-nitrophenol reduction, dye degradation, and textile effluent treatment

Nitroaromatic chemicals, including 4-nitrophenol (4-NP) and dyes, pose substantial risks to human health and the environment. Various catalysts that facilitate the reduction of 4-NP to 4-aminophenol (4-AP) have been documented to reduce its toxicity. Herein, we developed a novel nanocomposite consisting of needle-like copper oxide nanorods immobilized with L-cystine functionalized polyglycidyl methacrylate integrated graphene oxide (Cys-PGMA@GO-CuO) nanocomposite. The formation of this nanocomposite was comprehensively characterized using various analytical techniques. X-ray diffraction revealed a semi-crystalline nature for pure PGMA/GO with a prominent peak at 2θ = 19.25°. The introduction of inherently crystalline CuO nanoparticles in Cys-PGMA@GO-CuO rendered the entire composite completely crystalline. Further, the photocatalytic efficiency of the Cys-PGMA@GO-CuO nanocomposite was evaluated through advanced oxidation processes (AOP) for treating various toxic pollutants in wastewater remediation. The nanocomposite efficiently degraded dyes like methyl orange (99.8%) and methylene blue (99.9%) in just 50 mins and reduced toxic 4-NP to 4-AP within 40 mins. We further investigated the optimal degradation conditions based on [oxidant], [dye], and the presence of scavengers to understand the rate of degradation. Notably, the composite exhibited remarkable recyclability and stability. The performance of Cys-PGMA@GO-CuO was further evaluated using real wastewater samples, achieving a remarkable decolorization of 99.5% in textile dyeing wastewater and 97.1% in methylene blue-contaminated tap water. These results demonstrate the promising potential of this nanocomposite as an economically viable alternative approach for removing various organic pollutants from wastewater. Additionally, its successful application in real water sample analysis suggests its significant potential for practical implementation in water treatment processes.

Advanced Approaches in Dyeing and Printing Wastewater Treatment: A Comparative Study of Physical and Chemical Methods

This thesis presents a comprehensive analysis of various physical and chemical methodologies for treating dyeing and printing wastewater, which is a significant environmental concern in the textile industry. It delves into physical techniques like ultrafiltration, nanofiltration, reverse osmosis, and magnetic separation, evaluating their efficiency in removing contaminants and the challenges faced, such as membrane fouling and the requirement for high-quality magnetic seeds. The study also explores chemical methods like electrochemical oxidation and photocatalytic oxidation, highlighting the advancements in electrode materials and the use of TiO2 catalysts in degrading pollutants. A comparison is made between the effectiveness, operational constraints, and economic viability of these methods, emphasizing the need for optimizing existing technologies and developing hybrid systems that integrate the strengths of individual techniques. This research aims to contribute to the ongoing efforts on enhancing wastewater treatment efficiency, reducing environmental impact, and promoting sustainable practices in the textile industry. This work serves as a reference for future research on wastewater treatment, offering insights into developing more effective, cost-efficient, and eco-friendly solutions.

Experimental and first-principle insight into Structural, optical and electrical properties and photocatalytic water purification application of Zn1-xMgxO

Environmental concern essentially demands solemn consideration of industrial waste-water containing organic dyes. To develop efficient photocatalysts for degradation of organic dyes in waste water, metal-oxide nanostructures are the promising candidate owing to their tunable physical properties. The present work emphasizes on the experimental and first-principle (DFT + U) studies to understand the impact of magnesium doping on the structural, optical and electrical properties, and photocatalytic degradation tendency of zinc oxide (ZnO) nano-ceramics. The ZnO lattice contraction endorsed by Mg-doping, has been examined mutually from the first principle calculations and Rietveld refinement investigations. The decrease in crystallite-size (93 to 88 nm) and enrichment in structural imperfections of Zn1-xMgxO nanostructures were analyzed with Williamson-Hall peak profile methods. The band gap broadening of ZnO with Mg doping was demonstrated by UV–visible spectroscopy (3.32 to 3.43 eV) which was further confirmed from DFT + U (3.39 to 3.55 eV) calculations. The increase in dielectric constant and reduction in ac conductivity has been observed due to Mg addition. The photocatalytic performance of Zn1-xMgxO nanostructures was evaluated under sunlight for Methylene-blue (MB) and Congo-red (CR) dyes. The performance has been optimally improved with 6 mol% Mg content leading to degradation of 86.2 % and 58.3 % of MB and CR dyes respectively in 160 min.

Constructing blocked-nanolayer by surface charge inversion over anion exchange membrane for improved antifouling performance

Anion exchange membranes (AEMs) with excellent antifouling property are essential for treating highly saline organic wastewater through electrodialysis (ED). In this study, we proposed a strategy of surface charge inversion to construct a blocked- nanolayer based on in-suit dopamine (DA) deposition followed by grafting negative-charged 2-acrylamide-2-methylpropanesulfonic acid (AMPS) for promoting the antifouling performance of AEM. It's indicated that the surface hydrophilicity and negative charge density was gradually enhanced with the increase of AMPS grafting density without sacrifices of ion exchange capability, swelling ratio and desalination performance. In the simulated fouling experiments, the optimal AEM-AMPS-105 membrane exhibited excellent antifouling property due to the improved surface hydrophilicity and high electrostatic repulsion against organic matter. It's highlighted that the transmembrane voltage of modified membrane after operating 200 min was reduced from 7.12 V to 4.85 V with a significant decrease of energy consumption by 55.1 % while maintaining a high current efficiency level of 85.5 %. Moreover, the modified membrane performed significantly enhanced salt/contaminant selectivity and high stability in dye wastewater treatment. We anticipated that the construction of charge-blocked nanolayer by surface charge inversion offered a practical method for improving the organic fouling-resistance of AEMs.

Polyelectrolyte electrostatically self-assembled modified porous polyacrylonitrile nanofibers as adsorbents for anionic dye removal

Herein, we chose PAN with good sunlight and weather resistance and easy surface modification as the electrospinning material to prepare the PAN nanofiber membrane. Then the surface modification of the obtained PAN fiber membrane was carried out sequentially by alkali hydrolysis and acid neutralization to make the surface of the fiber membrane negatively charged. Finally, the positively charged polyelectrolyte PAH on the surface was selected as the functional material, and a simple and environmentally friendly electrostatic self-assembly method was adopted to modify the prepared PAN nanofiber membranes labeled as PAN@PAH. This treatment effectively increased the storage space and adsorption groups of the fiber membranes, which led to a significant increase in the removal ability of anionic dyes in wastewater. In particular, the PAN@PAH nanofiber membrane adsorbed 439.66 mg/g of methyl orange and 946.83 mg/g of Congo red, which showed better adsorption capacity than many other membranes reported in the literature. Moreover, the adsorption capacity of PAN@PAH remained at 90.19 % after eight adsorption-desorption cycles. The preparation method and modification strategy of this membrane adsorbent provides new ideas and methods for the removal of other anionic dyes.

Performance investigation on a self-powered microbial pollutant adsorption cell with N-LAC/PVDF cation exchange membrane

A high-efficiency, self-powered microbial pollutant adsorption cell with an N-LAC/PVDF cation exchange membrane was proposed to remove metal ions and organic dyes in high-salt wastewater. Nitrogen-doped alkali lignin (N-LAC) was synthesized using chitosan nanoparticles (CS) and alkali lignin (AL) using a blending method. The N-LAC/PVDF cation exchange membrane was prepared by chemically grafting polyvinylidene fluoride (PVDF). With modification, hydroxyl, carboxyl, carbonyl, and other hydrophilicity groups were introduced into the cation exchange membrane. The addition of N-LAC improved the membrane's hydrophilicity and adsorption capacity. FITR and SEM, respectively, characterized the surface morphology of the exchange membrane. The result showed that the contact angle reached 74.89° when the amount of N-LAC was 1 wt.%, and the desalination efficiency was 93.5 %, which increased by 70 %. The adsorption capacity of organic dye Pb and metal ion MB was 91 % and 94 %, respectively, showing an increase of 31.9 % and 43.5 %.

Decoupling synthesis and crystallization of covalent organic frameworks (COFs) for more crystalline layer targeting high efficiency dye separation

Covalent organic frameworks (COFs) are crystalline porous materials composed of organic building blocks linked by covalent bonds, which have attracted great attention for membrane–based separation applications. However, fabrication of COF membranes with high quality and performance remains a challenge, especially for the β–ketoenamine linked COFs. In the conventional IP methods, the synthesis process (the Schiff–base reaction of the monomers and the tautomerism of the oligomers) and the crystallization process (the self–assembly of the oligomers) of the COFs materials occur simultaneously on the surface of the support membrane, which can result in low crystallinity, high defect density, and poor separation performance of the COF layer. In this study, a novel strategy for fabricating large-area, defect–free COFs composite membranes by interfacial polymerization (IP) was presented to overcome this problem. By incorporating both the amine and aldehyde monomers in one organic phase, and dissolving organic acid catalyst in another phase (the water), the synthesis process mostly take place in the bulk of the organic phase, while the crystallization occurs on the surface of the support membrane under the influence of the organic acid catalyst. This strategy effectively decoupled the synthesis process with the crystallization, providing a stable growth region for crystalline layer, ultimately leading to the formation of a thin, defect–free and highly ordered COF layer on the support membrane. The strategy was demonstrate by synthesis of triformylphloroglucinol phenylenediamine (TpPa)–Ⅱ/Poly(m–phenylene isophthalaminde) (PMIA) composite membrane. We characterize the structure and morphology of the TpPa–Ⅱ/PMIA composite membrane by various analytical techniques to verify our hypothesis, and evaluate its separation performance using pure water permeance and dyes retention rate as indicators. The results show that the TpPa–Ⅱ/PMIA composite membrane has an 80 nm thick top-layer with regular COF structure and orderly pores. It exhibits an excellent dye separation performance, with a (pure water permeance) PWP of 105.6 L·m−2·h−1·bar−1 and CR rejection of 99.2 %, which surpasses most of the TpPa–type COFs composite membranes reported in literature, as well as the reference (TpPa–I/PMIA membrane) in this work. Moreover, the TpPa–Ⅱ/PMIA composite membrane maintains both its performance and structural stability during a 240–hour cross–flow filtration of the dye solution, demonstrating its excellent potential in the dye wastewater treatment.

Enhanced photo-Fenton degradation of dyes under visible light with recyclable γ-Fe2O3/CQDs: Catalyst preparation, performance and mechanism insight

A low band gap and visible light-responsive heterogeneous Photo-Fenton catalyst of γ-Fe2O3/CQDs micron composite was prepared under the one-pot hydrothermal method. The Photo-Fenton degradation of γ-Fe2O3/CQDs towards dye solution of rhodamine B(RhB), methyl blue (MB), and methyl orange (MO) was studied comparatively with α-Fe2O3. The γ-Fe2O3/CQDs exhibited remarkable catalytic performance for various dyes and with a first-order rate (k) of 14 times higher than that of initial α-Fe2O3 with a low concentration of H2O2 of 0.049 mmol. L−1 and a wider pH range of 3.1–7.1. The microstructure of the compounds was observed by XRD, SEM, TEM, FT-IR, and XPS characterization results suggested that the γ-Fe2O3/CQDs nanocomposite was formed through the stable Fe–O–C bonds, thus, the band gap decreased, and it is more favorable for the distance of holes and electrons. The free radical trapping experiment and EPR analysis indicated that •OH and 1O2 were the major active species during the typical photo-Fenton reaction. What's more, the γ-Fe2O3/CQDs also exhibited good stability and magnetic properties. DFT conclusion shows that the mechanism of the potential determination step (PDS) on α-Fe2O3(220) is the cleavage of H2O2 with an energy barrier of only 0.08 eV, which is 0.54 eV lower than that of OH* on γ-Fe2O3(220). Thus it can be deemed that γ-Fe2O3/CQDs perform much higher catalytic activity for the dissociation of H2O2 than α-Fe2O3. This work gives a feasible and economical countermeasure of visible light Photo-Fenton dispose of dye wastewater with a recyclable magnetic γ-Fe2O3/CQDs micron catalyst.

Sulfuric acid-assisted ball milling for the preparation of Si-O-enriched straw biochar: removal efficiency of rhodamine B and adsorption mechanism.

Traditional pyrolysis biochar has been widely employed to treat dye wastewater. However, there are some problems in the pyrolysis process, such as the generation of harmful gases and the low content of silico-oxygen functional groups to promote adsorption. Straw biochar (Ac-BCbm) was prepared by sulfuric acid co-ball milling method. The adsorption performance and adsorption mechanism of rhodamine B (RhB) under different preparation conditions and factors were investigated. The results showed that the adsorption rate of Ac-BCbm on RhB was up to 94.9%, which was 60.5% and 55.8% higher than that of ball-milling straw (STbm) and biochar prepared by pyrolysis (STBC600), respectively. The Ac-BCbm had better adaptability under different pH and common interfering ions for remove RhB. Characterization and DFT simulation analysis revealed that the sulfuric acid co-ball milling process promoted the formation of Si-OH and Si-O-CH3 oxygen-containing functional groups of Si component in straw, which enhanced the hydrogen bonding interactions and effectively improved the adsorption efficiency. This study investigated a new strategy for biochar preparation by sulfuric acid co-ball milling, which provides an additional development direction for the efficient resource utilization of straw.

Discerning the catalytic treatment of cationic dye wastewater in photoreactor comprising ternary (Co3+/Co2+)-embedded SnO2/ZnFe2O4 composite sensitive toward ultra-violet illumination.

Herein, magnetic (Co3+/Co2+)-integrated SnO2, SnO2/ZnFe2O4, and ZnFe2O4 composites have been prepared from triply distilled water and 30% of isopropanol in the water medium. The phase evolution, microstructure, and magnetism were investigated successfully and tested for cationic dye wastewater degradation containing Rhodamine 6G and Methylene Blue under ultra-violet irradiation. Composite spheres are attributed to efficient heterojunction interfaces between ZnFe2O4 and SnO2 semiconductors with the support of (Co3+/Co2+) nanoparticles. The results provide a simple, low-cost, environmentally friendly, and scalable method of ternary composites to degrade mixed dyes. Co3+/Co2+-implanted SnO2/ZnFe2O4 offered narrowed bandgap energy, more light absorption, diminishing electron-hole recombination, and more charge carriers toward cationic dye wastewater than the binary components. The rate constant of Rhodamine 6G degradation was observed at 0.0237min-1, and Methylene Blue degradation was observed at 0.0187min-1 at 90min under UV (λ = 365nm) irradiation. Capturing studies of various organic reactive species and mechanisms of composites was also proposed in detail.

Green synthesis of iron nanoparticles using mulberry leaf extract: characterization, identification of active biomolecules, and catalytic activity.

The synthesis of iron-based nanoparticles (Fe NPs) using traditional preparation methods suffered from the disadvantages of high cost, environmental harm, and easy agglomeration. In this study, a novel eco-friendly method was proposed for the synthesis of iron nanomaterials (ML-Fe NPs): using antioxidant components extracted from mulberry leaf to reduce divalent iron (II). The preparation conditions of ML-Fe NPs were optimized by orthogonal tests. The prepared ML-Fe NPs exhibited an amorphous core-shell structure, displaying excellent dispersion and stability. During the synthesis process of ML-Fe NPs, the polyphenol molecules in mulberry leaf extract played a dominant role. A possible synthetic mechanism involving complexation, reduction, and encapsulation was proposed. Furthermore, the ML-Fe NPs were utilized to construct an ML-Fe NPs/peroxymonosulfate catalytic system for the degradation of Rhodamine B dye wastewater. The ML-Fe NPs demonstrated remarkable catalytic potential, achieving a 99% degradation efficiency for Rhodamine B within a span of 40min.

Construction of gradient SA-TiO2 hydrogel coated PVDF-g-IL fibre membranes with high hydrophilicity and self-cleaning for the efficient separation of oil-water emulsion and dye wastewater

The industrial wastewater filtered by water treatment membranes is very complex in practical applications, therefore, it is a challenge to prepare a membrane with large pore size and high flux that can efficiently separate various wastewater containing pollutants of different scales. To solve this problem, an SA-TiO2 hydrogel-coated PVDF-g-IL composite fibre membrane with super hydrophilicity, anti-pollution, and pH-responsive self-cleaning properties has been designed and prepared by electrostatic spinning and layer-by-layer coating techniques in the present work. The super hydrophilic gel layer on the surface gives the composite membrane efficient separation capability while maintaining rapid passage of the aqueous phase; the underlying PVDF-g-IL fibre membrane is positively charged and removes not only anionic/cationic pollutants by electrostatic repulsion or attraction but also creates an ionic bond with oppositely assigned SA so that the gel layer tightly bond to the base membrane. The PVDF-g-IL@SA-TiO2 membrane achieves stable and efficient separation of oil-water emulsions and dye wastewaters with a high filtration flux while retaining a retention rate higher than ∼95%. After multiple self-cleaning cycles, the ultra-thin gel layer still offers satisfactory durability with ≈100% flux recovery. This study provides a promising new strategy for designing efficient multiple contaminant separation and simpler self-cleaning membranes.